The present invention relates to the processing of substrates in a substrate processing chamber. More particularly, the present invention relates to improved apparatus and methods for reducing particle contamination in the processing of substrates in a substrate processing chamber.
In the fabrication of semiconductor-based products (e.g., integrated circuits or flat panel displays), the substrate (e.g., the semiconductor wafer or the glass panel) may be processed in multiple processing steps. Some of these processing steps, such as etching, deposition, stripping, ashing, and the like, may be performed in a substrate processing chamber utilizing any number of suitable source gases. The source gas may be introduced under pressure into the substrate processing chamber via one or more gas ports.
In the case of a plasma etching reactor, the etchant source gas molecules are excited to form a plasma to etch a substrate in the plasma processing chamber. The plasma reacts with the exposed areas of the substrate surface to remove materials from the exposed areas, forming etch byproducts in the process. The etch byproducts are then exhausted away from the plasma processing chamber to maintain the density of the reactive species at a desired level and to reduce the accumulation of particulate contaminants on interior surfaces of the plasma processing chamber as well as on the substrate itself. After processing is completed, a purge process may be performed to evacuate the chamber interior of any remaining etch byproducts, thereby preventing the particulate contaminants created during one process from contaminating subsequent processes.
As the density of semiconductor devices increases, it becomes increasingly important to minimize the introduction of particulate contaminants onto the surface of the wafer and/or chuck to ensure the integrity of the process and to increase yield. In the past, efforts to reduce particulate contaminants within the substrate processing chamber have included, for example, periodic cleaning of the chamber interior, selecting process parameters and source gases that produces fewer particulate contaminants, reducing the surface areas within the plasma processing chamber on which particulate contaminants can accumulate, and the like.
However, little if any attention has been paid to the design of the inlet gas ports and its role in contributing to the introduction of particulate contaminants onto the substrate surface. This is because inlet gas ports by their nature are intended to introduce uncontaminated source gas (i.e., a gas that is relatively free of particulate contaminants) into the substrate processing chamber. Thus one typically would not look at the inlet gas ports and particularly the behavior of the gas jets that emanate therefrom when trying to address the problem of particulate contamination on the substrate surface.